Thank you! The idea of restarting cars that are in a gridlock is worth considering. Currently the cars have no way to escape in terms of pathfinding, as the rails they follow are blocked. One of the cars could reverse to clear the gridlock while others wait, or there might be an alternative path that the car can follow that bypasses the gridlock. Once I have improved the pathfinding to allow one of the solutions above, I can elect one of the cars as the leader (which is similar to stoppping/restarting) to avoid gridlocking again.